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Vision 1 Flashcards

1
Q

What is the eyeball derived from?

A

The embryonic brain.

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2
Q

What part of the neural tube becomes the cerebral hemispheres and the eyes?

A

Rostral

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3
Q

What ate the neural and pigmented layers of the retina derived from?

A

Optic vesicle.

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4
Q

What are the sclera and choroid derived from?

A

Embryonic menengeal tissues.

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5
Q

What is the lens derived from?

A

Ectoderm (not neural tissue).

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6
Q

What does the vitreous body contain in the embryo?

A

Hyluronic acid and type II collagen fibrils (slowly replaced)

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7
Q

What vestige of the hyloid artery is used to nourish the embryonic lens?

A

Hyloid canal

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8
Q

What are visual specs, reminants of the hyloid artery, that are too large to be phagocytosed?

A

Floaters

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9
Q

What are the 3 layers of the eyeball?

A

Fibrous coat, vascular coat, nervous coat

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10
Q

What is the fibrous coat homologous to?

A

Dura

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11
Q

What is the vascular coat homologous to?

A

Arachnoid and pia

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12
Q

What is the nervous coat homologous to?

A

CNS

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13
Q

Where do the extrinsic muscles of the eye insert?

A

Sclera

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14
Q

What is sclera?

A

Dense, white CT

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15
Q

What is contiguous to the sclera but clear to allow light to pass through to the retina?

A

Cornea

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16
Q

How does the cornea get nutrients?

A

Through diffusion of the aqueous humor

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17
Q

What 3 structures regulate the refraction of light?

A

Lens, ciliary body, and iris

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18
Q

What is the choroid?

A

Layer of anastomoses

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19
Q

What makes up the vascular coat?

A

Choroid and structures for regulation of light refraction

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20
Q

Most refraction of light is done by what structure?

A

The cornea

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21
Q

The remaining refraction of light not done by the cornea is variably controlled by what?

A

The lens

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22
Q

What is the function of the curvature of the lens and cornea?

A

refract radially separating rays of light at different degrees. This causes the light rays to converge back to a point.

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23
Q

How does the lens get its nutrients?

A

From the aqueous humor, through diffusion.

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24
Q

How does the lens control light refraction?

A

By changing its convexity.

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25
Increased convexity of the lens focuses the light from a closer source for what?
near vision
26
decreased convexity focuses the light from a more distant source for what?
far vision
27
Where does the lens focus light?
Onto a point on the retina.
28
Light from what sources diverges more and requires greater refraction and lens contraction
nearby
29
Light from what sources is close to parallel and requires less refraction by the lens
far
30
What affects where the lens focuses light?
Eyeball length
31
What is it called when the eyeball is too long and light is focused in front of the retina?
Myopia (near sighted)
32
What is it called when the eyeball is too short and light is focused behind retina?
Hyperopia (far sighted)
33
What two things Resting is convexity of lens | is maintained by?
Suspensory ligaments from the ciliary body and internal elastic fibers.
34
What produces an inherent tendency of the lens to bulge, i.e. increase the convexity of the lens?
internal elastic fibers
35
What makes the lens capsule elastic?
Collagen IV and glycoprotein
36
What produces new cells during life?
Germinal zone
37
After migration from germinal zone, what happens to the cells?
cells lose their nuclei and become transparent.
38
What is is the age-related loss of resting convexity caused by loss of elasticity?
Presbyopia (far sightedness)
39
What is is the reduction of vision due to opaqueness of the lens?
Cataracts
40
Significantly, what is increased in older and in cataractous lenses?
Level of iron
41
What are zonule fibers that extend from ciliary body to the equatorial perimeter of the lens?
suspensory ligaments
42
What are 2 functions of the suspensory ligaments?
Maintain resting tension and decrease convexity of lens by outward tension along its circumference
43
What alters the convexity of the lens?
ciliary muscles
44
What is it called when the ciliary muscles actively relax suspensory ligaments to increase convexity?
accommodation
45
Radial fibers pull ciliary processes in which direction?
forward
46
What do circular fibers do to the lens?
diminish circumference of suspensory ligaments
47
Which part(s) of the ciliary muscle relax the tension in the suspensory ligaments allowing the intrinsic elasticity of the lens to increase its convexity for close vision.
both
48
Ciliary processes secrete what into anterior and posterior chambers
aqueous humor
49
What are the anterior and posterior chambers partitioned by?
the iris
50
What absorbs humor into veins?
Schlemm's canal (sinus venosus sclerae)
51
What disease causes the build up of fluid pressure due to inadequate drainage into Schlemm’s canal?
glaucoma
52
What contains pigmented striations of CT, | blood vessels & smooth muscle?
the iris
53
What is stroma?
CT with melanocytes
54
What absorbs and refracts different frequencies (colors)?
Melanin
55
What is continuous on posterior surface of iris; completely absorbs all light restricting incoming light to within pupil?
Pigment epithelium
56
What is a genetic trait that involves distribution of melanin pigments in the iris?
eye color
57
What is eye color determined by?
Different patterns of light refraction by melanin.
58
If there are no blue or green iris pigments, what causes blue eyes?
melanin is mostly on the deep surface | of the iris and Blue spectrum is maximally refracted from the deep surface and eyes appear blue
59
What causes brown or green eyes?
melanin is more evenly distributed through the iris CT which refracts more of the light spectrum producing more color possibilities
60
What colors are brown eyes a combination of?
blue, green, red, and yellow light
61
What structure controls the aperture of the pupil?
The iris
62
What affects the range of focus?
Smaller pupils increase the range of focus; wider pupils decrease it.
63
Which muscle constricts the pupil and reduces incoming light?
Sphincter Pupillae
64
Sphincter pupillae is sympathetic or parasympathetic?
parasympathetic
65
Which muscles Opens pupil & increases incoming light?
Dilator pupillae
66
Dilator pupillae are sympathetic or parasympathetic?
sympathetic
67
Where do parasympathetic nerves of the pupil travel?
Along oculomotor nerve (CNIII)
68
Where is the ciliary ganglion? Parasympathetic or sympathetic?
Posterior of the eyeball; parasympathetic
69
Where does sympathetic activity arise from?
Upper thoracic levels of the spinal cord
70
Which structure consists of postganglionic neurons that project axons along arteries to the iris?
Superior cervical ganglion.
71
What constricts the pupil?
Parasympathetics
72
What contacts the lens, sympathetic or parasympathetic?
Parasympathetics
73
Where are parasympathetic preganglionic neurons located?
Within the Edinger-Westphal nucleus.
74
What is the name of one of the nuclei of the oculomotor nerve that contains the parasympathetic preganglionic neurons?
Edinger-Westphal nucleus
75
Whereis the Edinger-Westphal nucleus?
Midbrain
76
What 2 things do parasympathetic postganglionic neurons in the ciliary ganglion activate?
Sphincter pupillae to constric the pupil and ciliary muscle to contract the lens.
77
What is the function of the pupillary light reflex?
Maintain homeostatic level of light entering the eye
78
_________ ganglion cells in the retina respond to ambient light.
Melanopsin
79
_______ coordinates both eyes.
Pretectal nucleus
80
What is the path of the consensual pupillary response?
Light to melanopsin ganglion cells to pretectal nucleus to Edinger-Westphal nucleus to ciliary ganglion to pupil
81
What is the consensual pupillary response?
Constriction of both pupils in response to light shone in one eye
82
What does sympathetic activity increase?
Light entry into the eye
83
Which neurons innervate the superior cervical ganglion (SCG) cells?
preganglionic neurons in T1,2
84
What 2 things does the postganglionic SCG neurons activate?
Dilator pupillae to open the pupil and tarsal muscle to raise the upper eyelid
85
What are 2 things the sympathetic control of the iris and upper eyelid regulated by?
Local reflexes and descending influences from the limbic system and hypothalamus during an emotional state.
86
What muscle is a smooth muscle just deep to the levator palpebrae superioris and attaches to the tarsal plate in the eyelid?
Tarsal muscle
87
What is the tarsal muscle innervated by?
Sympathetic nerves
88
What is the function of the sympathetic control of the tarsal muscle?
To raise upper eyelid in emotional states
89
What is the name for a drooping eyelid?
Ptosis
90
What is the name for the condition that includes ptosis?
Horner's syndrome

Organ Systems III (13 decks)

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